"Our greatest responsibility is to be good ancestors."

-Jonas Salk

Monday, August 9, 2010

A Moderate Approach to an Extreme Problem

Well, there are spectra of opinion, but let's go with the three bears approach.

First, you can believe that the risks of anthropogenic global warming are trivial, consequential, or vast.

Second, you can believe that the social changes required to solve sustainability issues are trivial, substantial, or fundamental. The libertarian believes that the changes are trivial, and will be borne by the marketplace without direct intervention. The radical environmentalist believes that the modern attitude is irreparable, and sustainability is an existential social question as well as an existential environmental question. The moderate view is that some adjustments are needed.

These are separate questions. Your opinion on one should really have no bearing on your opinion on the other. That leaves nine possible opinions.

More to the point, they are different kinds of question.

The first is not a question of political philosophy at all. It is simply a question of fact; the dominant questions are physical, chemical and biological. It is not "radical" to believe that the risks are severe, nor is it "reactionary" to believe that the risks are trivial. It's pretty much either right or wrong.

I believe the risks are severe.

The second is a question of political philosophy. Can the modern, post-Soviet, market-oriented worldview survive as is? Does it need some adjustment? Or must it be scrapped altogether. Here, I think the labels of "radical" and "reactionary" are quite appropriate, and this is where the dangers of immoderate beliefs lie.

I am a moderate. I think we can find our way through this without huge disruption to our culture, which has much to say for itself. I think the risks of extreme cultural change are real enough. History teaches us that absolutism is a great risk itself.

But I think it's obvious, looking at the evidence, that carbon emissions must stop. (Update - In response to comments, I mean here NET carbon emissions. As Arthur put it in a recent message, the carbon either has to stay in the ground or go back in the ground. We cannot use the ocean as a carbon dump.) I find myself being cast as an "extremist" for saying this in public discussion, even though it's pretty much what the entire expert community believes. No. After decades of gross neglect, the problem has gone from manageable to extreme. But it's not "extremist" to say so.

In short, I think we can preserve the modern western freedom and most of the prosperity, and indeed make it better in some ways. It's not automatic. It won't be easy. I don't think we can afford a revolution any more than we can afford the status quo. We have to fix our creaking, out of date and out-of-touch societies to be in touch with the world around us. The next century will, hopefully, not be as awful as the first half of the last one was, but we'll need to be very smart to avoid the future being much worse than what we have had recently. We can preserve individual freedom, a functioning marketplace, and collective security while eliminating extreme poverty, just as we always intended. But we have to work at it.

That's a centrist, middle-of-the-road position. It's just the problems that have, from thirty years of neglect, gotten extreme.

Update: Check out Andrew Sullivan on the liberal/conservative divide. (Yet another hat tip to Scruffy Dan here.) A correspondent writes the following very interesting reflection:
Is it possible that, at this level – the principled, humane, calm, smart, broad-minded, pragmatic, courteous, inclusive, reality-based level – there really is no difference between conservative and liberal? That once having ascended the peak to actual, functional intellectual, emotional and spiritual adulthood -- to human maturity -- the paths of liberal and conservative meet, as they say all spiritual paths do?

Maybe we are all both conservative and liberal all along. Ask yourself: if you won a new car on some game show, but could only have one of the following two options, which would you choose – brakes, or an accelerator? The answer, of course, is every car needs both, just as every person, and every polity, needs both brakes (conservatism) and accelerator (liberalism) – and hopefully, both in good working order.
The only thing I might disagree with is which is the brake and which the accelerator, these days. The words seem to me to have lost much meaning beyond a sort of cultural cohesion.

Image: Avi Katz


King of the Road said...

You've rarely written anything with which I can agree so wholeheartedly. And, as you know, you and I have islands of disagreement ;)

This is a very useful set of distinctions.

Steve Bloom said...

In that case you'll both find Andy Revkin's latest quite depressing. I flame him (we'll see if he lets it through:

'Well, Andy, you do have your little memes, don't you? Somebody with the privilege of a venue like this should be a bit more careful with the fact-checking.

'Certainly there was a bad flood in the Indus basin in 1929, but does "worst since" indicate that this year's wasn't worse? No. All it actually says is that there wasn't a worse one in between. So, I looked into it.

'Three minutes of googling found this Australian article, and while it may seem odd to use the Oz for fact-checking I doubt they had any reason to make up figures in this instance. Cutting to the chase:

'"That 1929 flood discharged 250,000 cubic metres per second (cusec) of water into the river systems. This month's discharge exceeded 440,000 cusecs."

'Now, I could never aspire to being as jaded as someone in your position and so am perhaps prone to over-excitement, but that sounds to me like an exceptional event, probably rather outside the range of natural variability. (And depending on how they're counting the second rainfall surge, that 440,000 figure may be revised upward.)

'It's also interesting how many of your commenters were willing to accept your incorrect slant at face value. I'd be a little embarassed if I were them.

'(Technical note: For discussing the climatic significance of this event, we care about the rainfall [for which discharge is probably a reasonable proxy], not the flooding [the extent of which will be affected by the presence of control structures].)

'Anyway, correction please, and a little more care in future.'

Alexander Ac said...


"carbon emissions must stop" is very extreme in a sense of achievability. I.e. current system as it is, can not achieve zero or close to zero carbon emissions.

One needs huge changes in society and energy infrastructure, if we want to fix global warming (and peak oil!). I just point to one problem: every day, we add 200 000 of new inhabitants... do I need to say more?

Anonymous said...

That's not really practical to say all carbon emissions must be stopped. Saying "an order of magnitude reduction" or something like that would be better in my view.

Michael Tobis said...

NET carbon emissions into atmosphere and ocean can be and must be stopped.

Indeed, that is arguably the same as saying that concentrations in air and in water can be and must be stabilized. (The argument is whether the soil and biota are included in the boundaries of the system.)

Unknown said...

MT, you said the same over at Keith Kloor's blog, but when challenged on your statement that the expert community says that, you were unable to show it. Can you do that now?

I note that you have changed the wording to 'the expert community believes that' net emissions must drop to zero. Same question--do you have any hard copy indications that the expert community does indeed believe that?

Unknown said...

I should also add my voice to King of the Road, that this post is quite good.

Michael Tobis said...

I did provide references to a couple of recent consensus documents at Kloor's.

Busy right now but I'll go fish them out soon.

Also, stay tuned. I plan to defend this point at some length.

Padraig Tomas said...


The following quote is tangentially related to your question.

From the United Nations Framework Convention on Climate Change:


The ultimate objective of this Convention and any related legal instruments that the Conference of the Parties may adopt is to achieve, in accordance with the relevant provisions of the Convention, stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner.

The convention entered into force on 21 March 1994. It was signed by the United States on 12 June 1992 by our former President George W. Bush.

I draw your attention to the "ultimate objective," and to the implication of the fact that some 194 countries have agreed that this goal is one worth achieving.

manuel moe g said...

quoting Tom:

> "I note that you have changed the wording to 'the expert community believes that' net emissions must drop to zero."

My view of MT's point: There is nothing special about zero. If you are slowly driving into a lake, and the front license plate is wet, you must eventually back out of the lake, lest lose the car. Some sensible assumptions about continuity imply that you must first stop, even if only momentarily, to change from forward to backward motion.

I agree with the spirit of Tom's overall point, as I understand it, that we all would benefit from the expert's own beliefs, stated without intermediary, in a helpful format.

Phillip Price, over at "Statistical Modeling, Causal Inference, and Social Science" blog, published probability distributions over climate sensitivity (degrees C per doubling of CO2).


This is a helpful way to communicate beliefs about climate. Read the post, and read the comments, and note how timid the denialists were to publish their own curves. Everyone is willing to draw their own curve (some with crayon), but *defending* it as more strongly supported by evidence than the IPCC's is the hard part.

Along the "climate sensitivity curve" is a vertical line that represents "95% chance that within 3 generations the USA population will drop to below 10,000,000, with the *lucky* ones living like the Amish or the Plains Indians". (Substitute likewise for your own country).

Since the IPCC has been consistently too optimistic with their hard numbers, I would tend to agree with the curve "Phil Current", and I would put that critical line between 4 & 5 degrees C, because the massive machinery of modern agriculture and distribution depends on mild weather. Higher temperatures will be great for kudzu, beetles, crickets, and possums, but I don't know how to turn that glistening biomass into stocked supermarket shelves - and stocked supermarket shelves are a prerequisite for our quality of life, in the urban USA.

(This is where Dick Tol will pipe up about the subgroup of the Amish that *prefers* beetle garnished possum meat, and where Dick will wail that only a modern day Stalin would deny them a boiling world. But I am the kind of creepy authoritarian that would keep a toddler from touching a hot stove, and so I am beyond reform.)

The area under the curve, to the right of the line, is more likely than snake-eyes, and little less likely than rolling 2 or 3 from a single roll of a pair of dice. Those are pretty good odds, *except* when you are rolling for the lives of your great-grandchildren. Some people are constitutionally incapable from drawing inference, but not all of us are so handicapped.

Human languages are notoriously terrible at communicating subtleties of chance and consequence, and very good for never-ending sophistry, so it would be nice to have those with the best ability to follow Phillip Price's lead.

Michael Tobis said...

Moe, nice points, nice link.

If you think about it, the only sustainable long term average growth rate for any quantity in a closed system is zero. The trick is to maintain that average without the quantity itself being zero.

Concentrations are cumulative (mass is conserved) any sustainable mass budget has to balance over the long term. Hence net emissions must go to zero over a long enough time. That doesn't account for time scales, of course, but it's an interesting place to start thinking about the problem.

William T said...

meanwhile, back in the real world, atmospheric CO2 is still rising exponentially, if not faster.

It's going to be a difficult process to turn that curve down again, particularly since there still lacks a political consensus that it really is a problem. That to me is the key issue. In any major crisis, there are groups of people opposed to making a response. Usually it requires some kind of critical event to push the political process into decisive action. As in previous crises, you need to be ready with a plan of action to put into place when the momentum for change starts to roll.

Tom said...

I have seen skeptics write something along the lines of, 'if zero net is what we need, we're all dead because it's never going to happen.'

Before I tell them that their opinion should not be sufficient to condemn the world, I would like to in fact know that the expert community explicitly states that.

The UNFCCC statement quoted in comments here is miles away from that. Single papers with probability distributions is likewise, miles away from that.

I'm prepared to tell skeptics they can't have what they want, for whatever my voice is worth (not much, as manuel, marco and dhogaza will be quick to tell you). But I do not seen the community of climate science rallying around the statement that net emissions must be zero.

Steve Bloom said...

"'if zero net is what we need, we're all dead because it's never going to happen.'"

Yeah, that's about right for a lot of them. They neglect the distinction between jumping and being pushed.

"Before I tell them that their opinion should not be sufficient to condemn the world, I would like to in fact know that the expert community explicitly states that."

See below.

"The UNFCCC statement quoted in comments here is miles away from that."

"(P)revent(ing) dangerous anthropogenic interference with the climate system" is entirely clear to me. Why not you?

"But I do not seen (sic) the community of climate science rallying around the statement that net emissions must be zero."

Have you reviewed the relevant documents, in particular the Copenhagen Diagnosis? Last time I checked, it did call for a rapid path to zero net emissions. Other than that, I would say Michael would tend to have a more reliable sense of this than you.

Tom said...

Mr. Bloom, the climate science community has not been at all shy about communicating what it believes, in full-page advertisements, jointly signed letters and editorials, petitions and that sort of thing.

If the climate science believed something strongly, such as MT surely does, and if it could be communicated so clearly, as MT so surely does, I expect we would have seen it.

Expecting me (or the rest of the world) to read what is shown here and to make the inference you want is an order of magnitude in difference.

There are possible explanations of why the belief could be widespread but not communicated--fear of alienating the public or ridicule of the position, or something else--but as I told MT on KK's blog, there is no sign of an explicit consensus on this issue.

I say this because, if there really should be, you all can go out and start collecting signatures. Because what you've got so far doesn't get the job done.

Michael Tobis said...

As I said, do stay tuned.

King of the Road said...
This comment has been removed by the author.
King of the Road said...


I don't see how this can conceivably be difficult. Regardless of whether you think carbon dioxide accumulation is a problem or not, if you accept that:

1. Carbon dioxide is very long lived in the atmosphere.
2. Mankind's oxidation of fuels consisting of carbon containing materials adds carbon dioxide to the atmosphere at a rate greater than sinks remove it.

Then the conclusion that NOT INCREASING the carbon dioxide fraction in the atmosphere requires, on average, net zero emissions is inescapable. Said differently, given 1 and 2 above, an average net emission rate greater than 0 must cause an increasing carbon dioxide fraction in the atmosphere. Similar problems are solved involving rates of ingress and egress of liquids in containers in about the second week of elementary differential equations.

I don't know who debates 1 and 2 so the only FACTUAL arguments must revolve around whether the increasing content is harmful. The policy arguments certainly can be about whether reduction to zero, mitigation, or doing nothing is the best societal course depending on where one stands on Michael's two axes.

I suspect that those who understand the two points above (how can it not be everybody?) AND who think the consequences would be severe hesitate to say that net emissions must be brought to zero because they see the consequences of even saying they must be cut at all.

Tom said...

KOTR, I can see the logic in what you're saying, but that has absolutely nothing to do with the existence of an explicit call from a body of climate scientists for a commitment to zero net emissions. Don't try and convince me--go out and get the petition signed.

Steve Bloom said...

Let's see, the Copenhagen Diagnosis says:

"The turning point must come soon: If global warming is to be limited to a maximum of 2°C above pre-industrial values, global emissions need to peak between 2015 and 2020 and then decline rapidly. To stabilize climate, a decarbonized global society – with near-zero emissions of CO2 and other long-lived greenhouse gases – needs to be reached well within this century. More specifically, the average annual per-capita emissions will have to shrink to well under 1 metric ton CO2 by 2050. This is 80-95% below the per-capita emissions in developed nations in 2000."

OK, "near-zero," but close enough IMHO.

the authors are an impressive group: I. Allison, N.L. Bindoff, R.A. Bindschadler, P.M. Cox, N. de Noblet, M.H. England, J.E. Francis, N. Gruber, A.M. Haywood, D.J. Karoly, G. Kaser, C. Le Quéré, T.M. Lenton, M.E. Mann, B.I. McNeil, A.J. Pitman, S. Rahmstorf, E. Rignot, H.J. Schellnhuber, S.H. Schneider, S.C. Sherwood, R.C.J. Somerville, K. Steffen, E.J. Steig, M. Visbeck, A.J. Weaver.

(Including no less than three RC authors, which is impressive.)

And of course they were synthesizing the views of the March 2009 Climate Congress, which was attended by 2,000+ scientists. Here's the list of topics and presenters.

So what's not to like, Tom?

Michael Tobis said...

Then there is this one:

• National Research Council, National Academy of Science, Climate Stabilization Targets: Emissions, Concentrations, and Impacts over Decades to Millennia, 2010.

From the executive summary:

The report demonstrates that stabilizing atmospheric carbon dioxide concentrations will require deep reductions in the amount of carbon dioxide emitted. Because human carbon dioxide emissions exceed removal rates through natural carbon “sinks,” keeping emission rates the same will not lead to stabilization of carbon dioxide. Emissions reductions larger than about 80 percent, relative to whatever peak global emissions rate may be reached, are required to approximately stabilize carbon concentrations for a century or so at any chosen target level.

So can we settle for "larger than 80 per cent"? Note that is globally. Since only roughly a fifth of us are doing most of the emitting, we have to cut that remaining 20% by at least a factor of 5. So now we are at a 96% cut from American levels, to stabilize the atmosphere.

Of course, to stabilize the ocean as well, you have to cut essentially all of it, as King of the Road explains.

The natural sink of CO2 is rock weathering, which equilibrates in nature with CO2 emissions from volcanoes on a half million year time scale. If you have a half a million years or so to wait around, I guess, the story gets more complicated.

So I guess we can settle for a 96% emissions cut in the US for a start. Does that help?

Alexander Ac said...

There is a relevant TOD article:

"The discussion about our energy supply is full of extremely optimistic expectations. There are many people who believe that full replacement of fossil with renewable energy sources in an extremely short time span is possible. Such ideas have been publicly voiced in Al Gore’s call for 100% renewable energy in the United States within 10 years, and Jacobson & Delucchi’s plan to power 100 percent of the planet with renewable by 2030 published in Scientific American. Their optimism stems from ignoring the inherent gradual nature of energy transitions and the quality differences between energy sources."

This is a review of recent book by Vaclav Smil:

Anonymous said...

Moe, the interesting link doesn't show fully, I think you have to divide it into short segments and put line changes into it.

Is it this?


Anonymous said...

What I find ironic is that Tom is calling for definitive proof of the existence an emerging consensus on "eventual net zero emissions".

He admits that the logic for this case is essentially inescapable. I can think, off-hand, of about a dozen papers that explicity explore this theme in the literature in the past two years - e.g. Matthews and Caldeira (2008). (It is hard to imagine having missed them if you are focussed on the issue!) And, he's been getting pointers to the 2009 Copenhagen Diagnosis, the 2009 Synthesis Report from the Copenhagen Congress ("Stabilising atmospheric concentrations at any level will require emissions
to be reduced to near-zero levels in the long term."), the 2009 WGBU (German Advisory Council on Global Change) report ("at the end of the budget period, i.e.
around 2050, a largely zero-emissions economy must
be in place, as the geophysical leeway in subsequent
decades is likely to be very limited and the accumulation
of CO2 in the Earth System, although just about
tolerable, will persist for some long time."), the 2010 NRC report...

And yet, all this doesn't seem to quite meet Tom's exacting standards. There needs to be a formal definitive consensus document!

But when there is a formal consensus document on a specific climate science issue? Such as the IPCC AR4 WG1 on climate sensitivity? Tom rejects the consensus estimate of ~ 3C and favours a personal estimate of a much lower sensitivity!

And we know how receptive Tom is to independent research of the literature. So, to what end are we working? Why are we wasting our keystrokes responding - other than it flushes out a few more references?

Michael Tobis said...

Rust, it's not Tom that raised the question, it's me. He's just picking up on my question and huffing and puffing a bit, but I'm the one who started asking the question.

I think the question is a good one.

Most people don't understand the realistic constraints on the emissions problem. Why they don't is an interesting question. There is a real gap between expert consensus and public discourse on emission targets which doesn't strike me as healthy.

EliRabett said...

Remember MT, Tom believes in the Pielke fairy, two buck/yr for research and all will be majically good

Tom said...

Hmm. I see a call for 80% reduction which you inflate to 96% by geographical segmentation, which may or may not be appropriate. That's not zero.

Please remember that I am not here to argue if your contention regarding the need to go to zero is correct. It may or may not be, and that's another argument.

I see a call for drastic reductions, I see a call for 80%, I see almost zero, I see 80-95%.

I'm not trying to quibble--in fact I'm trying to help you. I see an area where there apparently should be a statement of consensus but where in fact there is none.

Is my assessment correct?

Tom said...

Silly Rabett, your tricks are for kids. We're all behaving well here, and then you show up with your usual schtick. If you can't play nicely, play somewhere else.

Tom said...

If I can ask, do these assumptions include CO2 from biofuels? Is the world allowed to use solid mass biostock for generating plants, ethanol or biodiesel for cars?

I actually may have the tools to generate a roadmap to near-zero emissions, but I would need the ground rules set before I started.

Michael Tobis said...

Eli, I presume that anyone signing themselves "Tom" here is Tom Fuller, and I haven't forgotten Tom Fuller's contributions to the discourse so far.

I have little doubt that Tom will be one of the people running for the cover of the Colorado conspiracy's distractions. It would fit his ever-so-reasonable but wrong pattern nicely.

Tom, yes you are quibbling.

It's 100% +/- 20%; somewhere between 80% and 120% reduction in net emissions as far as the eye can see, converging on 100% in the long run.

We need to get to 80% ASAP and pass through 120% on the way to a long term average of 100%. There is nothing special about the 100% number as far as the economy goes if sequestration is in the mix; it is, however, a special number as far as stabilizing the system is concerned.

As I said, I will happily settle for 95% reduction in the west as a target in my lifetime, as opposed to, say, doubling or tripling, thanks very much.

Tom said...

20% is quibbling?

And I don't get at all your foolish complaints about the Pielkes. It's destructive, not based on fact, and leads you into error.

Other than a healthy respect for what they've tried to do (and in some cases succeeded in doing) I have no affiliation with them, so your snide accusations just make you look even more paranoid and out of touch.

As my contribution to the discourse so far has been pretty much to serve as a punching bag for you and your acolytes, I'm glad you remember. Just remember this--I came here to try and help.

Go play with Eli.

Steve Bloom said...

Focus on the Copenhagen Diagnosis, Tom. It's global, it involved a very large number of climate scientists, and the "near-zero" is a nod to the obvious fact that some very small amount of emissions (e.g. from agriculture) can't be completely eliminated.

You got what you wanted, so now behave.

Michael Tobis said...

Is the difference between 80% and 100% cuts quibbling? Not in general, but under circumstances where we are headed in the wrong direction, and where 120% "cuts" are meaningful, yes.

Anonymous said...

Tom, maybe we could try it this way:

If we cut our net CO2 emissions by 80% - by your reckoning, would atmospheric (and ocean) CO2 concentrations go up or down?

Or, to put it another way, when our global emissions WERE historically just 20% of today's level, were concentrations going up or down?

Or, plausibly explain how concentrations COULD come down with net CO2 emissions at a level much above zero? (On some sort of societally-meaningful time-frame - say, several hundred years or so, not "rock-weathering" stuff...)

P.S. Also - what Steve Bloom said...

Paul Daniel Ash said...

Tom, the only way it's not quibbling would be if it would have made a significant difference had MT written:

But I think it's obvious, looking at the evidence, that carbon emissions must be cut to zero: somewhere between 80% and 120% reduction in net emissions as far as the eye can see, converging on 100% in the long run... pretty much what the entire expert community believes.

It's really hard to see how that in any way alters the point. Perhaps you can explain.

Michael Tobis said...

If Tom doesn't get the point, he doesn't get it.

I oversimplified just a tad on Collide-a-Scape a couple weeks ago and he is still trying to nail me on it. To the extent that is his intent, it's just gotcha games, not a serious discussion. So I'd appreciate just scaling back to "at least 80%" just to get the discussion on a reasonable footing, and off the hair-splitting (sorry Eli).

But when Tom Fuller raises the issue that the point that very deep cuts are needed hasn't been communicated effectively to the public or the politicians, and that (presuming it is the consensus) it should be, I agree.

I reiterate that the difference between 100% and 80% will not make a lot of difference to westerners if it is distributed equitably around the world. That is a second point, which Tom hasn't even bothered to take notice of.

Global per capita emissions must go below 5% of current western nations' per capita emissions to meet the 80% global cuts and avoid a colonial exploitation situation where some nations do most of the damage and others take most of the consequences.

Steve Bloom said...

Not to ignore the biofuels issue, I think it's still a matter of debate whether they net-zero emissions, but even if they're not one can still consider them as an interim solution. Regarding corn ethanol specifically, it seems clear by now that its gotten a failing grade in either context.

Michael Tobis said...

If Tom doesn't get the point, he doesn't get it.

I oversimplified just a tad on Collide-a-Scape a couple weeks ago and he is still trying to nail me on it. To the extent that is his intent, it's just gotcha games, not a serious discussion. So I'd appreciate just scaling back to "at least 80%" just to get the discussion on a reasonable footing, and off the hair-splitting (sorry Eli).

But when Tom Fuller raises the issue that the point that very deep cuts are needed hasn't been communicated effectively to the public or the politicians, and that (presuming it is the consensus) it should be, I agree.

I reiterate that the difference between 100% and 80% will not make a lot of difference to westerners if it is distributed equitably around the world. That is a second point, which Tom hasn't even bothered to take notice of.

Global per capita emissions must go below 5% of current western nations' per capita emissions to meet the 80% global cuts. We need to avoid a colonial exploitation situation where some nations do most of the damage and others take most of the consequences.

So to the majority of readers of this blog, who are in English-speaking countries and/or Europe, we are looking at very nearly total elimination of emissions even at the 80% global cuts level.

Anonymous said...

I think people (myself included) would get it better if the concentration would be plotted too. A logistic curve.

I don't know what would happens in the long term with say 20% (15-25%) of current emissions... what happens to the concentration and for example biological processes etc. I don't have a good enough idea of the carbon cycle.

Then there's the Gaia theory of negative feedbacks of the biosphere. How come has the CO2 been relatively steady for the last 8000 years when the temperature's been steady? Let's assume there is a negative biosphere feedback of some sort. Can such small emissions continually happen that they still stay in the "comfort zone" of this mechanism? I have no idea. Who does?

I hear that the earth system models and simulations are still very uncertain.

Given even our still lacking knowledge of how a basic forest exactly functions and exchanges carbon and stores some of it into the ground in the long term, I just don't have a very good idea.

Anonymous said...

80% is hard but 95% is much much harder in my first estimate opinion.

Even if you build nukes for electricity and electrify transport, you still need to make concrete and steel, grow livestock, farm and ultimately, breathe. The last fruits hang very very high.

Of course, offsets etc start playing some role when we're talking of small enough emissions. Accounting semantics. But for now, a practical person is talking about reducing emissions, which is the majority of the problem. Let's worry about those details later. Let's concentrate on the first 60 or 80%.

I estimate 20 tons CO2 per capita in USA can be dropped to 6 tons in France in some believable time frame and with great but not impossible cost and effort. That's 70%!

This should be very strongly campaigned for. Every second we speak the coal plants are spewing CO2.

EliRabett said...

AFAEK, the ag ghg emissions are mostly nitrous oxide, which means, ta...ta, to kill that off there go nitrogen fertilizers. THAT would make it pretty hard to feed the bunnies in our current system. (of course, we don't yet have those solar tractors. . . )

Of course, what does Eli know?

Anonymous said...

And, to add one more comment. I do agree that some more energy research should be done. The US had a vibrant nuclear research and development sector but it was gradually killed.

Of all the decades-scale future energy technologies that I've seen, breeder reactors seem like a very good bet. They require solving of relatively ordinary engineering problems, not new physics, and they require very little fuel. They can be built and operated by the majority of heavily CO2-producing countries, meaning they can enable massive CO2 cuts. They can be built so that they produce little long lived waste.

Solar and wind can also help. They have improved, but especially with the former it's not something one can bet much on from a physics point of view - ie it's more like an empirical observation like Moore's law.

We are probably going to need everything we can get, and then some.

Of course, if a price for carbon would be set, much of this would happen naturally and much much much more efficiently than just putting government money into research.

Anonymous said...

dr Rabett, that's true, and one very much neglected issue, given that N2O is a very strong greenhouse gas.
I've heard though that there are techniques to greatly diminish direct laughing gas emissions from the fields. Probably putting the fertilizer grains inside the earth or something like that.

Not much attention has been paid.

Same with cow diets that can make a
difference, I've heard.

Again, if emissions had a price...

Michael Tobis said...

Breathing doesn't count. It amounts to double counting the agriculture.

If the N2O is long-lived we do have a problem...

I do not claim that eliminating net CO2 emissions is sufficient but I had thought it was the hardest part.

William T said...

Tom, in all this debate between "80% reduction" and "zero net emissions" you need to also remember that in addition to human emissions, there are huge natural processes cycling CO2 in and out of the atmosphere. Without human input they are in balance. Even with human input, they manage to suck up about half of our emissions (although most of that is absorption into the ocean, which has other problems). So to stabilise atmospheric concentrations (which is the explicit goal) human emissions need to get down to a level where they are balanced by natural absorption processes. That may not be at zero "anthropogenic" emissions. And hence scientists aren't falling over themselves to say that we must stop ALL anthropogenic CO2 emissions.

My guess (FWIW) is that more than 80% reduction will be needed. Atmospheric CO2 was evidently increasing back when our emissions were last at that level. However, there is more than one way to skin a rabbit, and we can do much more to stimulate absorption of CO2 from the atmosphere to suck up the last few gigatons of human emissions.

William T said...

The problem with Ag emissions is methane - ruminants are walking anaerobic digesters (not to mention rice paddies) - so probably rabbits are not so bad after all...

manuel moe g said...

quoting MT:

> "hair-splitting (sorry Eli)"


I don't would want a hare-remover applied to this thread, but Eli seems to be a Tom-remover. We got the Fuller Brush-off ;-)

Padraig Tomas said...

In the text of the the quote from the UNFCCC document the words "stabilization of greenhouse gas concentrations in the atmosphere" are used. Greenhouse gas concentrations can not be stable unless the net emissions are zero. The notion that this is were we need to go is implicit in all that I have read to date in the peer reviewed literature as well as in the popular literature which puts forward the proposition that increased atmospheric concentrations are problematic.